Drip irrigation emitters are generally known in the art for use in delivering irrigation water to a precise point at a predetermined and relatively low volume flow rate, thereby conserving water. Such irrigation devices typically comprise an emitter housing connected to a water supply tube through which irrigation water is supplied under pressure. The drip irrigation device taps a portion of the relatively high pressure irrigation water from the supply tube for flow through a typically long or small cross section flow path to achieve a desired pressure drop prior to discharge at a target trickle or drip flow rate. In a conventional system, a large number of the drip irrigation devices are mounted at selected positions along the length of the supply tube to deliver the irrigation water to a large number of specific points, such as directly to a plurality of individual plants.
Subsurface drip emitters provide numerous advantages over drip emitters located and installed above ground. First, they limit water loss due to runoff and evaporation and thereby provide significant savings in water consumption. Water may also be used more economically by directing it at precise locations of the root systems of plants or other desired subsurface locations.
Second, subsurface drip emitters provide convenience. They allow the user to irrigate the surrounding terrain at any time of day or night without restriction. For example, such emitters may be used to water park or school grounds at any desired time. Drip emitters located above ground, on the other hand, may be undesirable at parks and school grounds during daytime hours when children or other individuals are present.
Third, subsurface emitters are not easily vandalized, given their installation in a relatively inaccessible location, i.e., underground. Thus, use of such subsurface emitters results in reduced costs associated with replacing vandalized equipment and with monitoring for the occurrence of such vandalism. For instance, use of subsurface emitters may lessen the costs associated with maintenance of publicly accessible areas, such as parks, school grounds, and landscaping around commercial buildings and parking lots.
Fourth, the use of subsurface drip emitters can prevent the distribution of water to undesired terrain, such as roadways and walkways. More specifically, the use of subsurface drip emitters prevents undesirable “overspray.” In contrast, above-ground emitters often generate overspray that disturbs vehicles and/or pedestrians. The above-identified advantages are only illustrative; other advantages exist in connection with the use of subsurface drip emitters.
There is a need to provide for a relatively constant water output from subsurface emitters, regardless of fluctuations in the water pressure in the supply tube. Without such flow rate compensation, water pressure fluctuations in the supply tube will cause corresponding fluctuations in the emitter water output. Such fluctuations result in the inefficient and wasteful use of water.
There is also a need in the irrigation industry to keep subsurface drip emitters from becoming obstructed, which results in insufficient water distribution and potential plant death. Obstruction of an emitter may result from the introduction of grit, debris, or other particulate matter, both from debris entering the emitter through the supply tube and debris entering the emitter from the terrain being irrigated, i.e., “back siphoning.” Such obstruction of an emitter may result in severe, and in some cases complete, flow restriction, potentially preventing the emitter from operating entirely. Many irrigation systems depend on the operation of each specifically situated emitter for sufficient water coverage to maintain healthy grass, crop, or other plant growth. Accordingly, there is a need to prevent subsurface drip emitters from becoming obstructed.
Further, there is a need to prevent obstruction of an emitter outlet by plant roots intruding into the outlet. Some conventional methods of preventing root intrusion, and the accumulation of microscopic organisms, involve the use of herbicides, fungicides, algaecides, biocides, etc. For example, in some instances, herbicides have been released indiscriminately into the soil in an attempt to prevent plant root intrusion. Alternatively, herbicides have been mixed with the plastic materials from which the irrigation supply tube is made. Also, such chemicals have sometimes been mixed in dilute quantities with the irrigation water distributed by the tube.
These conventional methods are often not directed specifically to the emitters and emitter outlets and, therefore, may be of only limited effectiveness in preventing root intrusion. In addition, such conventional methods generally target plants and the environment indiscriminately and may have serious adverse effects on the health of plants, as well as the broader environment as a whole. Accordingly, there is a need for a mechanism that is more targeted and more environmentally friendly.